This invention relates generally to irrigation water sprinklers of the arm driven type suitable for mounting on a center pivot, and, more particularly, relates to relatively large sprinklers of this type which include a reversing mechanism for part-circle watering.
Sprinklers of this type have a sprinkler body mounted for rotation on a substantially vertical axis, to receive water supplied through a vertical riser type, a removable sprinkler nozzle attached to the sprinkler body to direct a stream of water outwardly from the sprinkler at an angle of about 10.degree.-30.degree. above the horizontal, an oscillating forward drive arm, and a reversing drive arm. Unlike smaller impact arm sprinklers, which typically utilize a torsional spring to urge an impact arm into the stream of water, sprinklers of the type with which this invention is concerned usually have a forward drive arm mounted for rotation about a horizontal axis near the nozzle. The forward drive arm has a deflector spoon at one end, and a counterweight at the other end to urge the spoon into the stream of water.
When the stream of water impinges on the deflector spoon, reaction forces operate to pivot the forward drive arm about its axis of rotation, and to apply an increment of angular movement to the entire sprinkler. When the sprinkler has been rotated through a preselected arc, a camming mechanism operates to rotate the reverse drive arm, and to move a reverse deflector spoon into the stream of water, thereby rapidly rotating the sprinkler in a reverse direction back to its starting point. One sprinkler of the foregoing general type is the Model 103 Rain Gun manufactured by Rain Bird Sprinkler Mfg. Corporation, of Glendora, California.
One difficulty in operating sprinklers of this type arises from the desirability of employing nozzles of various sizes for various irrigation applications. When a relatively large-diameter nozzle is used, the reverse drive arm moves the sprinkler in a reverse direction with a very large accelerating force. The reverse movement can be so rapid that there is a significant risk of injury to anyone standing nearby, as well as a likelihood of increased wear and possible damage to the sprinkler itself. Of course, movement of the reverse drive arm can be adjusted to allow a smaller portion of the reverse deflector spoon to enter the water stream, thereby reducing the reverse accelerating force and obviating the problem. However, when a nozzle of different size is again installed, readjustment is always necessary.
It will therefore be appreciated that there has long been a need for an improved sprinkler of the foregoing general type which includes some means associated with its reversing mechanism for automatically compensating for nozzles of different sizes. The present invention satisfies this need.